Hi Michael,
I assume you are using transaction launcher to open account statement screen of remote system (ECC Tcode). If that is the case, since Transaction launcher uses logical system and not directly RFC destination, could you please check if the assignment of logical system to RFC destination is fine?
Since this was a system refresh, there is a high possibility that in your transaction launcher setting the id of the logical system got changed (from the refreshed system) and that logical system is not defined in your working system at all.
we can give this a try and check if everything is fine at logical system definition and transaction launcher settings side.
Hope this helps.
Regards,
Divya